Thermosetting resins and process of preparing same



Patented Mar. 24, 1953 N I T EAD PATENT O F F ICE THERMO'SETTING'RESINSAND 'PRofc'E's 's or PREPARING George E. Niles, Winchester, Mass ass'i'gn'cr to Monsanto Chemical Company, St; lL'o'uis, 7Mo., a corporation of Delaware No :Drawing. lzxpplicationjoctober' 29, 1949, Serial No. 1245492 to novel thermosetting resins which are suitable for addition to paper pulp in the heater for the production of paper sheeting having a high wet strength, "This invention also relates more particularly to processes for the production of improved thermosetting resins which are suitable for imparting wet strength characteristics to paper products.

It is one object of the present invention to provide novel nitrogen-containing thermos'et'ting resins.

A iurtherloblect of this invention is to provide water-soluble and highly condensed thermos'etting resins which are characterized by good stability inaqueous solutions, and which are capable of f'imparting improved Wet strength to paper products in which they are incorporated.

A further object of this invention isto provide simple andeffic'ient 'pr'oce'ss'e's'for the preparation of improved water-soluble and highly condensed thermosetting resins.

"Stil'h'fur'ther objects and advantages of this invention will be apparent from the following 1 description and the appended claims. Thefobjeots of this invention are attained, in general, by reacting, in water, an amino compound containing from 1 "to 6 carbon atoms and the grouping fonic acid having the general formula:

v-o-cne soau where R .is selected from the group consisting or an aryl radical and a hydroxy alkoxy radical containing not more than 4 carbon atoms, and Y is selected from the group consisting of H when R is a hydroXy alkoxy radical and OH when R is anaryl radical, for example, a salt such as hYdroxy-B" sodiul'n sulfo diethyl ether. The reaction is allowed to proceed until the resulting g 1-2 resin contains organic sulfonate residues as part of the resin cmolecule.

The proportions of the amino compound, the aldehyde and the water-soluble salt of zhydroxy organic sulfonic acid used may he varied widely depending upon the end use :of the resin ous products. Thus, it is possible, for example, to employ from 0.5 to 2 molecular proportions of the aldehyde for each amino group in the amino compound and tram- 0113 to 1 molecular .pI-opor tion or the salt of the hydroxy organic 'sulfonic acid of each imoleoular proportion ofyth'e amino compound, smaller and larger amounts of the aldehyde and such salt may also be used in some instances. In those instanceswhereit is desired to prepare water-soluble resins it generally de'e siraule to use from 2 to 6 molecular proportions of formalriehydeandifrom 0;05 to 1 molecular proportion of the salt of the hydroxy organic sul ionic acid for each molecular proportion of the amino compound. I

.As examples of suitable water-soluble salts of the hydroxy organic sulfonic acids which come within the scope of the compounds hereinbefore defined may be mentioned the sodium salt of phehyl isethionic acid having the structural formula and oqhydroxy-p" sodium sul'fo diethyl ether having the structural formula HO-CH2-CH2-Q-CH2-CH2-S'O3-Na and the like. Instead of the sodium salts other water-soluble salts-are also used such asthe other alkali metal salts, for example, the potassium and lithium and like salts. The preferred compound for use in preparing the resinous products or this invention is the sodium salt of 'phenyl isethionic acid. 7

The water-soluble salts of the hydroiry organic sulfonic acid may be added as such to the solution containing the amino compound and the aldehyde or the reaction product thereof, or the acid per se may be added to such solution together with a water-soluble base such as an alkali metal base, for example, alkali metal hydroxides or carbonates in an amount sufiicient to neutralize such acid. Thus, the salt is formed in the solution in situ.

benzaldehyde, furfural and such aliphatic aldehydes as acetaldehyde, propionaldehyde and the like and polymers of formaldehyde such as paraformaldehyde. Formaldehyde or paraformaldehyde are preferred, however, since they react more rapidly with the amino compounds and also yield reaction products therewith which have greater water-solubility than those prepared from other aldehydes.

The resinous products of this invention are suitably prepared by first reacting the amino compound and the aldehyde in an alkaline aqueous solution to form an aldehyde-amino compound condensation product having at least one a t-OH terminal grouping. In the case of form-aldehyde a methylol group -CH2OH is formed in place of one of the hydrogens on the amino group of the amino compound. In the case of urea and urea type compounds, the pH of the solution is generally between about 7.0 and 8.5. In the case of amino-triazines such as melamine the pH of the solution is generally between 7.0 and 10.0. The reaction between the aldehydeurea condensation products and the salt of the hydroxy organic sulfonic acid and the further condensation of the resulting product is carried out in an acid aqueous solution which, in general, has a pH between about 4.0 and 6.0. The aldehyde-melamine condensation products, on theother'hand, are reacted with the salt of the hydroxy organic sulfonic acid and are further condensed, in an alkaline aqueous solution which, in general, has a pH between about 7.0 and 10.0. The pH range for preparing the resinous prod-ucts of this invention is thus within the range of 4.0 to 10 depending on whether urea or melamine type resins are prepared.

Heating the solution or the reaction mixture above room temperature during the reaction between the aldehyde and the amino compound and during the reaction between the aldehydeamino compound condensation product and the salt of the hydroxy organic sulfonic acid increases the rate of reaction and is preferred.

However, both of these reactions should be carried out below the boiling point of the solution or mixture for'best results.

The resinous products of this invention contain organic sulfonate residues or groups attached to the resin molecule. Illustrative of such residue are the following:

to maintain the alkalinity of the mixture.

The terminal carbon atoms on the aliphatic chain of such residue is believed to be connected with the amino compound-aldehyde reaction product through an oxygen ether linkage in which the oxygen is attached to such terminal carbon atom. The exact mechanism of the reaction between the amino compound-aldehyde condensation product and the salt of the hydroxy organic sulfonic acid is not understood but it is believed that the hydroxy group of the acid reacts with one of the terminal groups of the amino compound-aldehyde condensation product with the splitting off of water. In any event, the final product contains organic sulfonate residues which materially alter the properties of the original amino compound-aldehyde condensation product.

Depending upon the conditions of the reaction, the aldehyde employed and the proportions of the reactants used, it is possible to produce resinous products which are water-soluble or water-insoluble, or which are solid and fusible or gel-like and fusible. It is also possible to produce resinous products which are water-soluble, but which have little or no wet strength imparting properties, and it is also possible to produce resinous products which are water-soluble and highly condensed and which impart a high degree of wet strength to paper products when incorporated therein. The water-soluble resinous products, in general, are suitable for the treatment of textile materials such as cotton or W001 yarns and fabrics. The water-insoluble or water-soluble resinous products can be made infusible and insoluble by heating and are useful in such form as cation-exchange materials. The water-soluble and highly condensed products which have been prepared in accordance with the preferred process described below are especially suitable for the treatment of paper pulp in the beater for imparting increased wet strength to paper products prepared therefrom.

A preferred process for preparing water-solluble and highly condensed resins which are suitable for imparting wet strength to paper products is described below. Such resins are prepared by first reacting 1 molecular proportion of urea with from 2 to 3 molecular proportions of formaldehyde, as formalin, in water until a methylolated u-rea is obtained. Best results are obtained by using 2.2 to 2.5 molecular proportions of formaldehyde. In most instances satisfactory results are obtained in subsequent reactions when the methylolated urea contains from 1.2 to 2 mols of combined formaldehyde. This reaction is carried out at slightly elevated temperatures, for example, at temperatures between about 50 and C. Moreover, the solution should be alkaline during the reaction. Satisfactory results are obtained at a pH between 7.2 and 8.5. For best results it is preferred to maintain the solution at a pH between 7.5 and 8.0. Norm-ally the pH is adjusted at the beginning of the reaction by the addition of a base such as an alkali metal hydroxide or carbonate, for example, sodium hydroxide or carbonate. In some instances the pH may drop as the reaction proceeds and further base is added The duration of the reaction is primarily dependent spea -zoo upon the-pH and temperature of the mixture. In general, the desired degree of methylolation of the urea is obtained Within a period of to 120 minutes.

It necessary to correlate the-pH and temperature-oi the mixture and the duration of the reaction to secure the best results. By increasing the temperature up to 770 C. and by lowering the pH toward 7.2, the reaction rate is increased. A reaction period of 15 minutes is usuallysatisiactory under such conditions. At lower temperatures and higher pH values a. reaction period of 120 minutes=may be required.

The solution or methylolated urea which is obtained in accordance with the foregoing procedure' is next' treated with the water-soluble salt of the hydroxy organic sulionic "acid. From10.05 to 0.5- molecular proportion of the sodium salt of phenyl isethionic acid, for example, is added to the solution of the methylolated urea for each molecular proportion of urea contained therein. in most instances it is preferred to employ from 0.05 to 0.3 molecular proportion of such salt'ifor each molecular proportion of urea since it is thus possible to obtain superior Wet strength resins.

After the addition of the sodium salt of phenyl isethionic acid or the other hydroxy organic sulionic acids previously defined, and while the solution of methylolated urea is still alkaline, the solution is concentrated without appreciably changing the degree of polymerization of the methylolated urea until the solution contains from about 55 to'65'% by weight of resin solids. Best results are obtained by concentrating to from 58 to 62% solids content. The solution is generally concentrated t therequisite solids content, With-out appreciably changing the degree of polymerization of the methylolated urea by vacuum concentration, or 'by flash concentration either with or Without the use of a vacuum. The solution is vacuum concentrated by subjecting it t a vacuum of at leastl0 millimeters of mercury .(absolute) and at a temperature not in excess of 65 C. By using a higher vacuum, that is, less than 15 millimeters of mercury and temperatures close to 65 C. the rate of concentration is increased. Best results have been obtained by subjecting the solution to a vacuum of 5 to 15 millimeters of mercury at a temperature of 55 to 60 C. l

The solution is flash concentrated by pumping it through a heated pipe, for example a jacketed pipe which is heated by steam, so that a small portion of the solution passing through the pipe from the pump to the outlet end of the pipe is concentrated tothe desired solidslcontent in a very short interval of time, for example, from 0.01 to 0.3 second and the solution is then cooled. When using the flash concentration procedure for concentratingthe solution it is necessary to correlate the temperature to which the solution is heated, the rate of flow and the diameter of the pipe so that the solution will be concentrated within. a very short period of time as defined above. Best-results havebeen obtained, from the standpoint of stability of the final product, by employing a vacuum during flash concentration, that is, by pumping the solution through a heated pipe which is at least partially evacuated.

By employing the vacuum concentrating or flash concentrating procedures as described above, it is possible to concentrate the resin solution to the desired solids content Without materially altering or changing the degree of polymerization of the methylolated urea. This is particularly important in-gthe preparation of wet strength resins since any :marked change in the degree of polymerization of themethylolated urea at this stage :of the process results in final products having interior wet strength properties. In some instances it may not be necesasryto concentrate the solution of imethylolated urea to the specified content since such solution mayicon tain the specified quantity of resin solidsasprepared.

Atter the resin solution has been concentrated to the desired solids content :as described above, it is acidified, that is, it .is rendered iacidic by the addition oi an acid, foruexample, a mineral acid such as sulfuric acid, phosphoric acid the like. The pH of the solution after acidification should be between about 4-15 and 5.5 .for best results. The solution is then heated 'to about a reaction between themethylolated 'urea and the sodium salt of phenyl 'isethionic .aacid. This reaction is generally 1 carried :out at :a temperature between about 180 and 95 C., care being taken to prevent boiling. It is usually desirable to carry out the reaction using a refiux condenser to avoid loss of water and a stirrer to minimize gel formation on the .heat exchange surfaces. The-resulting resin condenses as the reaction proceeds and eventually reaches a high state of condensation as is evidenced by a continued rise in the viscosity :of the solution. If the'condensation of the resin is carried too :far :aegel-like resin is obtained. The rate of condensation is largely dependent on the pH of the solution :an'dthe temperature to which the solution is heated. The rate of condensation increasing at higher temperatures and lower .pH values. The resin solution is heated at the temperatures andlpH values indicated above until the viscosity of the solution at .60% :resin solids contentis between about .5 and 10 poises as measured by the Gard,- ner-Holdt bubble viscometer. At these viscosi-ties the resin has maximum wet strength properties and is highly condensed.

Further condensation of the resin is substantially prevented or minimizedby making the solotionalkaline by the addition "of a water-soluble base after the solution has reached the desired viscosity. Any water-soluble base which does not precipitate the resin may be usedfor this purpose including the alkali metal hydroxide or carbonates such as :sodium hydroxide or carbonate, or a quaternary ammonium hydroxide such as trimethyl benzyl ammonium hydroxide. The amount of base added should be sufiicient to render the solution alkaline or alkaline reacting, and preferably should be sufficient to provide a solution having a pH between about 7.5 and 8.5. It is preferred to make the resin solution alkaline, as described above, before the solution is allowed to cool.

The resin solutions obtained according to the foregoing procedure consist of a water solution of a water-soluble, highly condensed thermos'etting resin and contain from .about to resin solids. Such solutions are infinitely dilutable and are quite'stable when stored at room temperature, and particularly in cold storage at a temperature above the freezing point of the solution. The resin particles in the solution are highly substantive to negatively charged cellulosic substances such as paper pulp fibers in the presence of aluminum ions, for examplathe aluminum ions derived from a solution of papermakers alum (aluminum sulfate) in water. This property makes these particular resins particularly suitable foraddition to paper pulp in the beater in the presence of alum since a predominant amount of the resin is picked up by or deposited on the paper pulp fibers and only minor amounts of the resin are lost in the white water after the paper-forming operation. However, these resins are not only highly substantive but also have the property of imparting high wet strength to paper products.

These resin solutions may be dried, if desired, for example, byspray drying, vacuum drying, drum drying and the like or by simple evaporation of water. By drying such solutions it is possible. to obtain solid products which are readily soluble in water and which have substantially the same properties as the original resin in solution. By using mild drying conditions, that is, relatively low temperatures, it is possible to form solid products which have the same and, in some instances, higher wet strength properties than the original resin as prepared. Such drying is bestcarried out by subjecting the solution to a vacuum of at least 40 millimeters of mercury and temperatures below the boiling point of the solution.

The wet strength resins prepared in accordance with the preferred process as hereinbefore described are normally incorporated in paper products by adding them to an aqueous slurry of paper pulp together with acids or papermakers alum, preferably alum, to render the resin substantive to the paper fiber. The resins are generally employed in an amount sufficient to provide from 0.25 to by weight of resin solids based on the oven dry weight of the paper pulp. Satisfactory results are obtained, in most instances, by using from 1 to 3% by weight of the resin. After the paper pulp has been formed into a paper product such as paper sheeting, the resin is cured in situ in the paper, that is, the resin is rendered insoluble and infusible in the paper product. This curing operation may be performed in various ways. One particularly convenient mode of operation consists in forming a paper sheeting in the customary manner, drying the sheeting on heated rolls and then winding the paper sheeting while it is still warm or .hot into rolls. By operating in this manner, the finished rolls, after removal from the paper-making machine, remain warm for several days and sometimes for a week in storage and the resin becomes infusible and insoluble under such conditions. If desired, the curing operation may be carried out by heating the paper at elevcated temperatures, for example, at 150 F. to 300 F. until the resin becomes insoluble and infusible. At such temperatures the resin is cured in the paper within a relatively short period of time.

A further understanding of this invention will be obtained from the following specific examples which are intended to further illustrate this invention, but are not intended tolimit the scope "thereof, parts and percentages being by weight unless otherwise specified.

One molecular proportion of urea and 2.7 molecular proportions of formaldehyde, in the form of a 37% aqueous solution, were stirred together and the pH of the mixture was adjusted between 7.5 and 7.9 with caustic soda. The mixture was then heated, with stirring, at 60 to 65 'C. for a period of 60 minutes. After this period of time 0.2 molecular proportion of the sodium salt of phenyl isethionic acid was added to the 8 solution. The solution was then concentrated until it contained 60% solids by subjecting it to a vacuum of 5 to 15 millimeters of mercury and concurrently heating the solution to a temperature of 55 C. and maintaining the solution at such temperature. The solution was then acidifled to a pH of 5 (glass electrode) by the addition of sulfuric acid, after which it was heated to a temperature of C. under reflux, with stirring, until the viscosity was 5 poises as measured with the Gardner-Holdt bubble viscometer. The pH was then adjusted to a pH of 7.5 to 8.0 (Hydrion paper) with caustic soda and the resin solution was then rapidly cooled to room temperature (about 25 C.).

The above resin solution was applied to paper pulp in the beater according to the following procedure. Bleached sulfite pulp was first refined to 350 c. c. Tappi (Technical Association of the Pulp and Paper Industries) Standard Freeness at 2% consistency in a laboratory refiner. Quantities of this refined stock suflicient to prepare hand sheets were used. To the refined stock was added a quantity of resin solution at 60% solids sufficient to provide 1.5% of resin solids based on the oven dry pulp solids. The resulting mixture was stirred for 15 minutes and then 3% of papermakers alum (aluminum sulfate), based on the oven dry pulp, was added and the whole stirred for an additional 15 minutes. This mixture was made into hand sheets on a Noble- Wood laboratory sheet machine. These handsheets were aged in an oven at C. for 4 hours to rapidly cure the resin and develop the wet strength. The sheets were cut into strips 15 millimeters in width and soaked in water for 16 hours. The wet sheets were then tested for wet tensile strength with a Schopper tensile tester. This testing procedure is described in greater detail in Tappi Testing Method T-456 M44. The wet strength of the sheets averaged 3.67 pounds per inch as compared to 1.75 pounds per inch for control hand sheet prepared from the same pulp but without resin treatment.

EXAMPLE II One molecular proportion of urea and 2.7 molecular proportion of formaldehyde, in the form of a 37% aqueous solution, were stirred together and the pH was adjusted between 7.5 and 8.0 with caustic soda. The mixture was then heated for 1 hour at a temperature of 60 to 65 C., after which 0.2 molecular proportion of B-hydroxy-fl' sodium sulfo diethyl ether was added. The resulting solution was subjected to a vacuum of 5 to 15 millimeters of mercury and maintained at a temperature between 45 and 55 C. until it contained 60% resin solids. The pH of the solution was then adjusted to 5 with sulfuric acid, after which the solution was heated at 95 C. under a reflux condenser and with stirring until the viscosity of the solution had reached 5 poises as measured by the Gardner-Holdt bubble viscometer. The pH of the solution was then raised to a pH of 7.5 to 8.0 (as measured by Hydrion paper) by the addition of caustic soda and the solution was then cooled to about 25 C.

The resin solution obtained in the manner described immediately above had good stability in storage at room temperature and was infinitely dilutable with water.

The above resin solution was applied to sulfite paper pulp in the beater using the same pulp and the same procedure described in Example I. Y l-Iand sheets prepared from the treated pulp were aoeazoo 9. dried for'hours at 1 Cato cure the resin and to develop the wet strength of the paper sheet. Strips of the hand sheet, the strips being 15 millimeters; wide, were immersed in water for 16 hours and testedfor wet tensile strength with a Schopper tensile tester. The wet strength-of the sheets averagedl 3l5 pounds-per inch as compared to 1.75 pounds per inch for a control hand sheet, that is-, ahand: sheet whichhad not been treated with resin. H H EXAMPLE I-IL Two separate solutions were first prepared-as described below Solution 1 One molecular proportion (126' parts) of mel aniinerand' 3.5 molecular proportions (283i parts) of formaldehyde, in the form-of a 37%. aqueous solution, were slurried by stirring and the pH of the resulting mixture was adjusted to 9.3 with sodium hydroxide. The solution was then heated to a temperature between 90" and 95 C. for about 2 to 3 minutes, after which a clear solution was obtained. v Solution 2 Thirty-five hundredths- (0.35) molecular proportion- (6.7.1. parts) of BhydroXy/3'"-sodium .sulfo diethyl ether. was added to 200 parts. of ;water.. The pH of. thissolution was adjusted to Kwithsulfuri'c acid and. then 0.5 molecularproportion. (375 parts.) of. formaldehyde, in. the form ofla.37% aqueous. solution Wasadded, after which the solution was. heated at 90 to 95 C. for

15 minutes andv then cooled: to 25C.

Solution 1 was added. to solution 2 and thepl-l of the resulting solution was adjusted to 8.0 with sodium hydroxide. The mixture Was then heated at a temperature of 90' to 95 (L for a periodof 15 minutes. The pH was. adjusted to 9.5 with sodium hydroxide, after which the solutionwas subjected to a vacuum of 30 to 35 millimeters of mercury at a temperature between 35" and 55 C.

until it contained 60% resinsolids.

This solution was infinitely dilutable with water and was suitable'for treating textile fabrics to provide a shrink-resistant finish.

After the solution allowed to stand over night (about 16 hours) it was heated at 90 to 95 C. for 30minutes, after-which time it had a viscosity of 13 poises as measured by the Gardner- Holdt bubble viscometer. The solution was cooled to 25 C. and diluted to 40% resin solids. The resulting solution was not infinitely dilutable with water, but was suitable for the treatment of textile fabricst Various modifications and changes may be made: inthe: processes of" this invention and in the startin materials used inthe preparation of the? resinous; products at this invention as: willbe apparent to those: skilled in: the art from a consideration f; the; foregoing description. It is accordingly intended: that the scope of this-inivention'. be" limited only by: the scope of the on form amethylolated urea; adding to the rest-lilting solution firom 0.05 to 0".5-"molecular= proportion of a water-soluble salt of a hydroxy or ganic sulfonic acid having the general formula:

where; R is selected from the group consisting. of anaryl radical and. a hydroxy alkoxy. radical containing not more than 4 carbon ator'ns and Y is selected from the group consisting of H when R is a hydroxy alkoxy radical and OH when R. is. an aryl radical; concentrating the resulting solution to a solids content of to by weight without materially changing the degree of polymerization of said methylolated urea; adding an aci'dto'the resulting. solution until the pH thereof is between about 4.5 and 5.5; heating. the solution at a temperature above about 01 but below the boiling point of the solution until the viscosity of the solution at" 60% by weight'r'esin solidsis" between about" 5 and 1 0 poises' as measured by the Gardner-Holdt bubble viscometer, and: then adding a watersolubl'e'base to the solution until" the solution is sufficiently alkaline to minimize further increases in viscosity of the solution. I g

2. A process substantially according toclaim 1, but further characterized in that the water'=-soluble salt of the hydroxy organic sulfonic acid is the sodium salt of phenyl isethionic acid.

3. A process substantially according to claim 1, but further characterized in that the water-soluble salt of the hydroxy organic sulfonic acid is fl-hydroxy-B-sod ium sulfo diethyl ether. I

4. A process of preparing paper products having a high wet strength which comprises treating an aqueous slurry of paper pulp in the presence of a substance-selected from the group consisting of acids andalumwith a water-soluble and highly condensed reaction product of 1 molecular proportion of urea, from 2 to3 molecular proportions of formaldehyde and from 0.05 to 0.5 molecular proportion of a water-soluble salt of a hydroxy organic sulfonic acid having the general formula:

where Ris selected from the group consisting. of an aryl' radical and a hydroxy alkoxy radical-containing. not more than 4 carbon atoms, andiwhere Y is-se'lected from the group consitsing oflHi when is; a hydroxy alkoxy radical. and OH: whenft is an aryl: radical, said reaction product having. a viscosity in water at 60% by weight solids content of5 to LOpoisesa-s measured-by the Gardner- I-Ioldt bubble viscometer and being supplied. in an amount sufficient to provide from 0.25 to 5 by weight-of said reaction product based on the overt dry weight of the paper pulpin said" slurry, forming said slurry into a paper productand then convertingsa-id'reaction. product in situ to the insoluble and infusible state.

5. A nitrogen-containingthermosetting resin comprising the water-soluble and highly condensed condensation product of (l) a neutral to alkaline condensate of 1" molecular proportion of an amino compound selected from the group consisting of urea, th'iourea, cyanamide, d-icyandiamide, guanid ine and. ami-notriazine having at least; two primary amino groups with from about 0.5: to 2: molecular proportionsbased. on each amino-groupin-said amino compound, of an. aldehyde and (2) from about 0.05 to 0.5 molecular proportion of a water-soluble salt of a hydroxy organic sulfonic acid having the general formula:

where R is selected from the group consisting of an aryl radical and a hydroxy alkoxy radical containing not more than 4 carbon atoms and Y is selected from the group consisting of H when R is a hydroxy alkoxy radical and OH when R is an aryl radical, said condensation product being further characterized in that an aqueous solution thereof at 60% by weight resin solids has a viscostiy between about and poises as measured by a Gardner-Holdt bubble viscometer, said resin having been prepared by the process of claim 12.

6. A nitrogen-containing thermosetting resin comprising the water-soluble and highly condensed condensation product of (1) a neutral to alkaline condensate of 1 molecular proportion of urea with from 2 to 3 molecular proportions of an aldehyde and (2) from about 0.05 to 0.5 molecular proportion of a water-soluble salt of a hydroxy organic sulfonic acid having the general formula:

where R is selected from the group consisting of an aryl radical and a hydroxy alkox'y radical containing not more than 4 carbon atoms and Y is selected from the group consisting of H when R is a hydroxy alkoxy radical and OH when R is an aryl radical, said condensation product being further characterized in that an aqueous solution thereof at 60% by weight resin solids has a viscosity between about 5 and 10 poises as measured by a Gardner-Holdt bubble viscometer, said resin having been prepared by the process of claim 13.

'7. A nitrogen-containing thermosetting resin according to claim 6,'but further characterized in that the aldehyde is formaldehyde.

8. A nitrogen-containing thermosetting resin according to claim 6, but further characterized vin that the aldehyde is formaldehyde and the water-soluble salt is fi-hydroxy-,3-sodium sulfo diethyl ether.

9. A nitrogen-containing thermosetting resin according to claim 6, but further characterized in that the aldehyde is formaldehyde and the water-soluble salt is the sodium salt of phenyl isethionic acid.

10. A nitrogen-containing thermosetting resin comprising the water-soluble and highly condensed condensation product of (l) a neutral to alkaline methylolated urea containing from about 1.2 to 2 molecular proportions of combined formaldehyde for each molecular proportion of urea and (2) from 0.05 to 0.3 molecular proportion of a sodium salt of a hydroxy organic sulfonic acid having the general formula:

where R is selected from the group consisting of an aryl radical and a hydroxy alkoxy radical containing not more than 4 carbon atoms and Y is selected from the group consisting of H when R is a hydroxy alkoxy radical and OH when R is an aryl radical, said condensation product being further characterized in that it is substantive to negatively charged cellulosic substances in the presence of aluminum sulfate and mineral acids, and an aqueous solution of the condensation product at 60% resin solids has a viscosity of between about 5 and 10 poises as measured by a Gardner-Holdt bubble viscometer, said resin having been prepared by the process of claim 17.

11. A nitrogen-containing thermosetting resin comprising the water-soluble and highly condensed condensation product of (1) a neutral to alkaline condensate of 1 molecular proportion of melamine with from 0.5 to 2 molecular proportions, based on each amino group of the melamine, of formaldehyde and (2) from about 0.05 to 0.5 molecular proportion of a watersoluble salt of a hydroxy organic sulfonic acid having the general formula:

i Y-C-CHz-SOaH where R is selected from the group consisting of an aryl radical and a hydroxy alkoxy radical containing not more than 4 carbon atoms and Y is selected from the group consisting of H when R is a hydroxy alkoxy radical and OH when R is an aryl radical, said condensation product being further characterized in that an aqueous solution thereof at 60% by weight resin solids has a viscosity between about 5 and 10 poises as measured by a Gardner-Holdt bubble viscometer said resin having been prepared by the process of claim 18.

12. A process of preparing nitrogen-containing thermosetting resins which comprises reacting 1 molecular proportion of an amino compound selected from the group consisting of urea, thiourea, cyanamide, dicyandiamide, guanidine and aminotriazines having at least two primary amino groups with from about 0.5 to 2 molecular proportions, based on each amino group in said amino compounds, of an aldehyde in an aqueous solution at a pH between about 7.0 and 10.0 to form an amino compound-aldehyde condensate, adding from about 0.05 to 0,5 molecular proportion of a water-soluble salt of a hydroxy organic sulfonic acid having the general formula:

where R is selected from the group consisting of an aryl radical containing not more than 4 carbon atoms and Y is selected from the group consisting of H when R is a hydroxy alkoxy radical and OH when R is an aryl radical, concentrating the resulting solution to a'solids content of about 55 to 65% by weight without materially changing the degree of polymerization of said amino compound-aldehydye condensate, adjusting the pH of the resulting solution between about 4 and 10 and heating the solution until the viscosity of the solution at 60% by weight resin solids is between about 5 and 10 poises as measured by a Gardner- Holdt bubble viscometer.

13. A process of preparing nitrogen-containing thermosetting resins which comprises reacting 1 molecular proportion of urea with from 2 to 3 molecular proportions of an aldehyde in an aqueous solution having a pH between about 7.0 and 8.5 to form a urea-aldehyde condensate, adding from about 0.05 to 0.3 molecular proportion of a water-soluble salt of a hydroxy organic sulfonic acid having the general formula:

tion to a solids content of about 55 to 65% by weight without materially changing the degree of polymerization of said urea-aldehyde condensate,,adjusting the pH of the resulting solution between about 4 and 6 and heating the solution until the viscosity of the solution at 60% by weight resin solids is between about and 10 poises as measured by a Gardner-Holdt bubble viscometer.

14. A process according to claim 13, but further characterized in that the aldehyde is formaldehyde.

15. A process according to claim 13, but further characterized in that the aldehyde is formaldehyde and the water-soluble salt is the sodium salt of phenyl isethionic acid.

16. A process according to claim 13, but further characterized in that the aldehyde is formaldehyde and the water-soluble salt is fi-hydroxyp-sodium sulfo diethyl ether.,

17. A process of preparing nitrogen-containing thermosetting resins which comprises reacting 1 molecular proportion of urea with from 2 to 3 molecular proportions of formaldehyde in an aqueous solution having a pH between about 7.0 and 8.5 to form a methylolated urea containing from about 1.2 to 2 molecular proportions of combined formaldehyde for each molecular proportion of urea, adding from about 0.05 to 0.5 molecular proportion of a sodium salt of a hydroxy organic sulfonic acid having the general formula:

i c-oHr-som gree of polymerization of said methylolated urea,

adjusting the pH of the resulting solution between about 4.5 and 5.5 by the addition of an acid, heating the solution at a temperature below the boiling point of the solution until the viscosity of the solution at 60% by weight resin solids is between about 5 and 10 poises as measured by a Gardner- Holdt bubble viscometer and adding a watersoluble base to the solution until the solution is sufliciently alkaline to minimize further increases in viscosity of the solution.

18. A process of preparing nitrogen-containing thermosetting resins which comprises reacting 1 molecular proportion of melamine with from about 0.5 to 2 molecular proportions, based on each amino group of the melamine, of formaldehyde in an aqueous solution having a pH between about 7.0 and 10 to form a, methylolated melamine, adding. from about 0.05 to 0.5 molecular proportion of a water-soluble salt of a hydroxy organic sulfonic acid having the general formula:

H Y--OHpSOaH where R is selected from the group consisting of an aryl radical and a hydroxy alkoxy radical containing not more than 4 carbon atom and Y is selected from the group consisting of H when R is a hydroxy alkoxy radical and OH when R is an aryl radical, concentrating the resulting solution to a solids content of about to 65% by weight without materially changing the degree of polymerization of said methylolated melamine, and heating the resulting solution while main taining the pH of the solution between about 7.0 and 10.0 until the viscosity of the solution at by weight resin solids is between about 5 and 10 poises as measured by a Gardner-Holdt bubble viscometer.

19. A process according to claim 4, but further characterized in that the water-soluble salt of the hydroxy organic sulfonic acid is the sodium salt of phenyl isethionic acid.

20. A process according to claim 4, but further characterized in that the water-soluble salt of the hydroxy organic sulfonic acid is ,H-hydroxy-psodium sulfo diethyl ether.

GEORGE E. NILES.

REFERENCES CITED UNITED STATES PATENTS Name Date Auten July 6, 1948 Number 

12. A PROCESS OF PREPARING NITROGEN-CONTAINING THERMOSETTING RESINS WHICH COMPRISES REACTING 1 MOLECULAR PROPORTION OF AN AMINO COMPOUND SELECTED FROM THE GROUP CONSISTING OF UREA, THIOUREA, CYANAMIDE, DICYANDIAMIDE, GUANIDINE AND AMINOTRIAZINES HAVING AT LEAST TWO PRIMARY AMINO GROUPS WITH FROM ABOUT 0.5 TO 2 MOLECULAR PROPORTIONS, BASED ON EACH AMINO GROUP IN SAID AMINO COMPOUNDS, OF AN ALDEHYDE IN AN AQUEOUS SOLUTION AT A PH BETWEEN ABOUT 7.0 AND 10.0 TO FORM AN AMINO COMPOUND-ALDEHYDE CONDENSATE, ADDING FROM ABOUT 0.05 TO 0.5 MOLECULAR PROPORTION OF A WATER-SOLUBLE SALT OF A HYDROXY ORGANIC SULFONIC ACID HAVING THE GENERAL FORMULA: 